A&A 455, 773-777 (2006)
M.-P. Véron-Cetty - P. Véron
Observatoire de Haute Provence, CNRS, 04870 Saint-Michel l'Observatoire, France
Received 9 March 2006 / Accepted 13 April 2006
Aims. This catalogue is aimed at presenting a compilation of all known AGN in a compact and convenient form and we hope that it will be useful to all workers in this field.
Methods. Like the eleventh edition, it includes position and redshift as well as photometry (U, B, V) and 6 cm flux densities when available. We now give 20 cm rather than 11 cm flux densities.
Results. The present version contains 85 221 quasars, 1122 BL Lac objects and 21 737 active galaxies (including 9628 Seyfert 1s), almost doubling the number listed in the 11th edition. We also give a list of all known lensed and double quasars.
Key words: galaxies: quasars: general - galaxies: Seyfert - galaxies: BL Lacertae objects: general
This edition contains quasars with measured redshift known to us prior to January 1st, 2006; as in the preceding editions, we do not give any information about absorption lines or X-ray properties. But we give the absolute magnitude for each object and, when available, 20 and 6 cm flux densities.
This catalogue should not be used for any statistical analysis as it is not complete in any sense, except that it is, we hope, a complete survey of the literature.
Table 1: Increase with time of the number of known QSOs, BL Lacs and Seyfert 1s.We have arbitrarily defined a quasar as a starlike object, or an object with a starlike nucleus, with broad emission lines and brighter than absolute magnitude MB=-23. The quasars are listed in Table_QSO. A sample page is shown in Fig. 1. Clearly, some objects would move from Table_QSO to Table_AGN and vice versa if other values for q0 and the spectral index were used or if an accurate B apparent magnitude was available for all objects. The variability may have a similar effect, as well as the size of the diaphragm used for the measurement as the contribution of the underlying galaxy for low-z quasars may not be negligible.
|Figure 1: Sample page of the QSO catalogue.|
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In Table_BL, we list all confirmed, probable or possible BL Lac objects with or without a measured redshift, without consideration of their absolute magnitude. As better spectra are becoming available, broad emission lines have been detected in a number of objects formerly classified as BL Lac; they have usually been moved to Table_QSO (Véron-Cetty & Véron 2000b).
Table_AGN lists "active galaxies'': Seyfert 1s, Seyfert 2s and Liners fainter than MB=-23. A number of galaxies with a nuclear H II region are also included (158), the reason being that they have been called AGN in the past and later reclassified; we consider it useful to keep track of these reclassifications to avoid further confusion.
Seyfert 1s have broad Balmer and
other permitted lines; Seyfert 2s have Balmer and forbidden lines of the same
width. Osterbrock (1977, 1981) has divided the
Seyfert 1s into five subgroups: Seyfert 1.0, 1.2, 1.5, 1.8 and 1.9 on the
basis of the appearance of the Balmer lines. Seyfert 1.0s are "typical''
members of the class, as described by Khachikian & Weedman (1971, 1974), while Seyfert 1.5s are objects
intermediate between typical Seyfert 1s and Seyfert 2s, with an easily apparent
narrow H profile superimposed on broad wings. The classes Seyfert 1.2 and 1.8 are used to describe objects with relatively weaker and stronger
narrow H components, intermediate between Seyfert 1.0 and 1.5 and
Seyfert 1.5 and 2 respectively.
In Seyfert 1.9, although the broad H emission is clearly
seen, broad H
cannot be detected with certainty by mere visual
inspection of the spectra.
We have adopted the more quantitative classification introduced by
|S1.2||2.0||< R < 5.0|
|S1.5||0.33||< R < 2.0|
|S1.8||R < 0.33||broad component visible|
|in H and H|
|S1.9||broad component visible|
|in H but not in H|
|S2||no broad component visible|
|Q2||type 2 QSO|
Seyfert 1 galaxies and QSOs, when viewed through the absorbing dusty torus have the same optical appearance; however, they differ either by their hard X-ray luminosity or, for radio loud objects, by their radio luminosity. It has become customary to call type 2 QSOs (or Q2) rather than Seyfert 2 the high luminosity narrow line objects. Treister et al. (2005) call type 2 QSOs narrow line objects with erg s-1 (H0=70 km s-1 Mpc-1) or >1042.3 erg s-1 if H0=50 km s-1 Mpc-1, while Derry et al. (2003) have more conservatively defined QSO2s as having an intrinsic, hard (2-10 keV) X-ray luminosity larger than 1044.3 erg s-1. Véron-Cetty & Véron (2000b) have shown that narrow line objects with a 178 MHz radio luminosity erg s-1 Hz-1 are QSO2s rather than Seyfert 2s.
In Table_AGN, 6875 objects have no classification. Most of them were originally classified as QSOs but turned out to be fainter than MB=-23 and were therefore moved to this table.
Table_reject lists the objects which once were believed to be AGN and are now known to be either stars or normal galaxies.
Table_QSO contains 85 221 objects, Table_BL, 1122, Table_AGN, 21 737 and Table_reject, 141. The catalogue is believed to contain all known quasars, BL Lac objects and Seyfert 1s.
Table_QSO, Table_BL and Table_AGN give:
1) Columns 1 and 2. The most common name of the object. For the meaning and the sources of the designations see Hewitt & Burbidge (1987), Fernandez et al. (1983) and Kesteven & Bridle (1977). For the sources discovered by the ROSAT X-ray satellite, we have used the following acronyms: RXS for the sources appearing in the All-Sky Bright Source Catalogue (Voges et al. 1999), 1WGA for the sources published in the WGACAT catalogue (White et al. 1994) and RX for the others.
When the name is preceded by an *, the object has not been explicitly associated with a radio source.
2) Columns 3 to 10. The best available J2000 optical or radio coordinates. The J2000 positions have been converted from the B1950 positions using the matrix given by Aoki et al. (1983). An O or an R following the coordinates means that the position is either an optical or a radio position measured with an accuracy better than one arcsec. An A means that it is only an approximate position which may be wrong by several arc minutes. No reference is given for the source of the positions. The availability of the Digitized Sky Survey (DSS) allows quick measurements of the optical position of any object brighter than 19.5 mag. It has already been used to measure the position of several hundreds QSOs (Schneider et al. 1992; Bowen et al. 1994; Kirhakos et al. 1994; Véron-Cetty & Véron 1996b). Optical positions with an accuracy better than 2 have also been measured for the 19 369 galaxies in the Zwicky catalogue (Falco et al. 1999) and for the 12 921 UGC galaxies (Cotton et al. 1999).
3) Columns 11 to 14. The 6 and 20 cm flux densities (in Jy) with references to the literature. When several measurements are available we took arbitrarily one of them. When a reference is given for the 6 cm flux density but the value of the flux density itself is left blank and there is an * in Col. 1, only an upper limit is available and this upper limit is not much greater than 1 mJy; in case there is no * in Col. 1, the reference refers to a detection but at a wavelength other than 6 cm.
The 20 cm flux densities have been taken mainly from the NRAO VLA Sky Survey (NVSS) (Condon et al. 1998) and the FIRST survey (Becker et al. 1995; White et al. 1997). The NVSS covers the sky north of (J2000.0 . The catalog contains 1 814 748 discrete sources stronger than mJy. The resolution was 45 FWHM. The rms uncertainties in and vary from 1 for the sources stronger than 15 mJy to 7 at the survey limit. The FIRST survey was carried out with the VLA. It covers an area of 9033 deg2 to a sensitivity limit of 1 mJy. The catalog contains 811 118 sources. Source positions are good to better than 1 . The beam size was 5 4. Identifications of FIRST radio sources with the 2001 version of the present catalogue were previously attempted by Wadadekar (2004) who found 775 coincidences.
4) Columns 15 and 16. The redshift as published. An * in front of the redshift means that it has been estimated from a low dispersion slitless spectrum and is of lesser accuracy or even plainly wrong as the emission lines may easily be misidentified. We have given only those values which are described as probable in the original sources and not the possible values.
5) Column 17. In this column an attempt has been made to classify the objects as S1, S1.0, S1.2, S1.5, S1.8, S1.9, S1i, S1h, S1n, S2, Q2, S3, S3b, S3h, S, S? or H2. Low redshift quasars are classified as S1 when a good spectrum shows that they are similar to Seyfert 1 galaxies.
In Table_BL, we find in this column:
|BL||for a confirmed BL Lac object.|
|BL?||for a probable BL Lac|
|blank||for a possible BL Lac.|
|?||for a questionable BL Lac|
|HP||for a Highly Polarized object.|
6) Columns 18 to 21. The V, B-V and U-B photoelectric or photographic magnitude and colours, when available (the survey of the literature for photographic colours may be incomplete) (an * in front of the magnitude indicates that the colours and the magnitude are photographic, while an R or an I indicates a red or an infrared magnitude). The column labelled "V'' gives the V magnitude when B-V is also given. When B-V is not given, this column usually gives the B magnitude, unless it is preceded by an R or an I. Maoz et al. (1993) have measured homogeneous V magnitudes for 354 QSOs with an accuracy of 0.1 mag; they have been included. For a few objects the O magnitude, measured on the blue Palomar Sky Survey plates, or the UK Science Research Council SRC-J Survey plates, believed to be accurate within 0.2 mag, has been extracted from the APS database (Pennington et al. 1993). For a number of objects we give the O magnitude, extracted from the USNO-A2 catalogue (Monet et al. 1996) or the Cambridge Automated Plate Measuring Machine (APM) catalogue (Irwin et al. 1994), recalibrated by E. Flesch (private communication); these magnitudes are flagged with an O. The O and Johnson B magnitudes are related by (Evans 1989).
|Figure 2: Correction to be applied to the absolute magnitude if H0=71 km s-1 Mpc-1, and rather than H0=50 km s-1 Mpc-1 and q0=0.|
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Table 2: Gravitationally lensed quasars. Column 1: name, Col. 2: short 1950 position, Col. 3: redshift of the quasar, Col. 4: redshift of the lens, Col. 5: separation in arcsec, Col. 6: references.
Table 3: Quasar pairs. Column 1: name, Col. 2: short 1950 position, Col. 3: redshift of the quasar, Col. 4: separation in arcsec, Col. 5: references (see Table 2).
For the SDSS objects we give V, B-V and U-B computed from u', g' and r' by the following equations (Fukugita et al. 1996):
7) Column 22. The absolute magnitude MB computed assuming
H0=50 km s-1 Mpc-1, q0=0, and an optical spectral
equal to 0.3 (Francis
et al. 1991), as follows:
In a more realistic flat cosmology with H0=71 km s-1 Mpc-1, and (see for instance Perlmutter et al. 1999 or Riess et al. 2004), the computed absolute magnitude would be systematically smaller than in the standard model adopted in the present paper. The correction to add to the absolute magnitude given in this catalogue is given in Fig. 2.
8) The next three columns (23 to 25) give the reference for the finding chart, the photometry and the redshift respectively. In many cases, the last reference in Table_AGN is that of the classification of the object (as a Seyfert or otherwise); in these cases the redshift can usually be found in Palumbo et al. (1983).
9) The B1950 position (Cols. 26 to 32).
Since the discovery in 1979 by Walsh et al. of the first gravitationally lensed quasar, Q 0957+561, a number of such objects (69) and of physical pairs with separation less than 10'' (38) have been found. They are listed in Tables 2 and 3 respectively. Mortlock et al. (1999) have stressed the difficulty sometimes encountered in distinguishing lensed quasars from physical pairs.
This research has made use of the APS catalogue of POSS I database which is supported by the National Science Foundation, the National Aeronautics and Space Administration, and the University of Minnesota. We are very grateful to E. Flesch and F. Ochsenbein for checking and improving the catalogue and we thank R. Monella for having brought to our attention a number of errors and omissions in previous editions.